I agree that building on an x86_64 host implies that SSE2 is available on the host while building, but does that imply that the built compiler and/or runtimes can only be used on x86_64 machines? Even though they are 32-bit binaries?
OK, build system is an area I’m not good at. So I may be wrong to understand it.
The problem looks to me is you generated a 64-bit configure file based the host, then directly applied it into 32-bit by only adding -m32.
Note, 32-bit and 64-bit modes can be pure software concept. We can switch to 32-bit mode on the same machine. In this case, the SSE2 is still avaliable. I assumed this is your scenario.
But if you want to make the 32-bit binary can be run on any 32-bit target, including that without SSE2 supported. Then I would say it is a misuse of such configure file, because it already assumed SSE2 available when been generated.